This invention is in the field of microcantilevers. This invention relates generally to use of microcantilevers to map absorption of electromagnetic radiation by a sample.
Microcantilevers have been employed in atomic force microscopy (AFM) for making contour maps of surfaces with extremely high sensitivity and resolution. While AFM has been extremely successful at mapping topography of samples at the micro and nanoscale, it has limited capability to characterize the chemical composition of a sample. Infrared spectroscopy is a benchmark technique that is widely used to analyze the chemical composition of a sample by measuring and/or mapping the absorption of infrared energy as a function of wavelength. Vibrational resonances in molecules create characteristic absorption peaks that allow identification and characterization of specific chemical species.
Recently, use of microcantilevers in infrared spectroscopic applications has been developed. Published U.S. Patent Application US 2006/0222047 and International Patent Application WO 2006/107991 describe use of microcantilevers to generate a three dimensional tomographical reconstruction and a nanoscale infrared spectroscopic micro-tomogram of a sample.
Published U.S. Patent Application US 2008/0283755 describes a technique for determining localized infrared spectra of a sample using an AFM probe. Lateral and vertical deflections of AFM probes in response to expansion of a surface due to absorption of infrared radiation are monitored to obtain infrared absorptions of the surface. By scanning the probe across the surface and using a variable wavelength infrared source, infrared spectroscopic maps of the surface can be obtained.
U.S. Pat. No. 6,452,170 describes methods for determining a force of interaction between a sample and a cantilever tip. Interactions are determined by measuring a plurality of points on the deflected cantilever and use of non-Hookian modeling to account for higher order vibrational modes to calculate the interaction force.
U.S. Pat. No. 6,935,167 describes methods for tuning resonance frequencies of a microcantilever. Published U.S. Patent Application, US 2009/0013770 discloses methods for probing multiple vibrational eigenmodes of a cantilever.